Winches are commonly used to lift and pull heavy loads. When they are overloaded they can fail in numerous ways which can lead to property damage and personal injury. Therefore, an overload sensor can provide an important safety feature. Because many winches are powered by an electric motor, the overload sensing is typically accomplished by monitoring how much electric power the motor is drawing. When the power draw of the motor exceeds a certain predetermined amount, the power to it is terminated. This stops the overload situation.
One drawback to this form of monitoring is its intrinsic inaccuracy. The measurement of the winch's load by measuring the power draw is susceptible to inaccuracies arising from power supply issues and bad electrical connections. It can also require complicated circuits and microprocessors.
What is needed, therefore, is a simple and direct way to measure the load on a winch while in operation.